What should I use for SMTP and API email?

If you’re choosing between SMTP and an email API, the short answer is:

• Use SMTP if you want a simple, universal way to send email from almost any app or server.
• Use an API if you want better reliability, easier integration, richer features, and better tracking/analytics.

Quick rule of thumb

• Transactional email from a modern app: use an email API
• Legacy systems or basic mail clients/tools: use SMTP
• Best overall for most software products: API
• Best for compatibility: SMTP

Why choose SMTP?

Pros:

• Widely supported
• Easy to plug into older software
• Works with standard email clients and libraries

Cons:

• Usually less feature-rich
• Harder to get good analytics, event tracking, and deliverability insight
• Can be more cumbersome for retries, logs, and templates

Why choose an API?

Pros:

• Easier programmatic sending
• Better error handling and reporting
• Webhooks for bounces, opens, clicks, complaints
• Often better deliverability tooling
• Templates, scheduling, suppression lists, etc.

Cons:

• Requires calling a provider’s HTTP API
• Slightly more vendor-specific

Recommendation

If you’re building a web app, SaaS, or backend service, I’d usually recommend:

• Primary sending via email API
• SMTP only if you need compatibility or have an existing SMTP-based setup

If you tell me what you’re using email for — like password resets, newsletters, app notifications, or a contact form — I can recommend the better option more specifically.